An information processing method and apparatus, a communication device, and a communication system. The method comprises: using a low density parity check (LDPC) matrix to encode input sequences to obtain a bit sequence D (501), a basis matrix of the LDPC matrix being represented as a matrix with m rows and n columns, each column corresponding to a set of Z consecutive bits in the bit sequence D, and n and Z both being integers greater than zero; and, on the basis of a bit sequence V, acquiring an output bit sequence, the bit sequence V being obtained by replacing each set of bits corresponding to at least two check columns in the bit sequence D (502). The present method can support high bit rate LDPC code performance requirements.